1. Field of the Invention
The present invention relates to a solid-state imaging apparatus and a camera, and particularly to a back-illuminated solid-state imaging apparatus and a camera with the solid-state imaging apparatus.
2. Description of the Related Art
As a solid-state imaging apparatus, an image sensor using a MOS (Metal Oxide Semiconductor) transistor (hereinafter referred to as a MOS-type solid-state imaging apparatus), which is a standard technology in IC manufacturing, has become widely used. The MOS-type solid-state imaging apparatus has an advantage in that it may not require a high drive voltage unlike a CCD (Charge Coupled Device) and it can be compact through integration with peripheral circuits.
The MOS-type solid-state imaging apparatus usually includes a readout circuit, such as an amplifier transistor, corresponding to each sensor (photodiode) that receives light and converts it into charges. In the MOS-type solid-state imaging apparatus, the readout circuit and wiring are disposed on the light incident side. The solid-state imaging apparatus with the readout circuit and wiring disposed on the light incident side is referred to as a front-illuminated solid-state imaging apparatus.
There is known a MOS-type solid-state imaging apparatus having a so-called multi-pixel sharing structure, that is, configured such that a plurality of sensors share a readout circuit in order to further reduce the space for the readout circuit and increase the sensor area in a pixel. For example, there have been proposed a solid-state imaging apparatus having a two-pixel sharing structure in which one readout circuit is provided for every two pixels (see JP-A-2005-150492), and a solid-state imaging apparatus having a four-pixel sharing structure in which one readout circuit is provided for every four pixels (see JP-A-2004-15298).
On the other hand, there has been proposed a back-illuminated solid-state imaging apparatus in which a readout circuit and wiring are disposed on the opposite side to the light incident side, as a technology for avoiding light-blocking wiring and increasing the sensor area (see JP-A-2003-31785).